Torsion bar cartridge extractor



J. F. OBRIEN ETAL TORSION BAP. CARTRIDGE EXTRACTOR Filed Jan. 2. 1964 Dec. 22, 1964 llll 1 FE; EJ-

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United States Patent Ofiice 3,161,978 Patented Dec. 22, 1964 3,161,978 TGRSEON BAR CARTRIDGE EX'ERACTUR John F. UBrien, Springfield, Mass, and Edward A.

Santos, Enfield, Conn, assignors to the United States of America as represented by the Secretary of the Army Filed Jan. 2, 1964, Ser. No. 335,442 5 Claims. (Cl. 42-25) (Granted under Title 35, US. Code {1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a cartridge extractor for automatic guns and is more particularly directed to means for resiliently mounting such extractor for pivotal movement in the forward end of a longitudinally reciprocal bolt.

In gins adapted to fire rimmed cartridges with an annular extraction groove adjacent the rear end thereof, the Withdrawal of the fired case from the firing chamber in the gun barrel is customarily accomplished by an extractor pivotally mounted in the forward end of the reciprocating bolt to engage the rim of the cartridge case during movement of the bolt into battery position. Such engagement is generally provided by a claw portion designed to ride over the rim on the cartridge case and enter into the annular grove under the clockwise bias of a suitable spring seated between the claw portion and the wall of the opening in. which the extractor is contained.

Although such arrangement ensures satisfactory extraction of the fired cart-ridge cases during the subsequent recoil movement of the bolt, the relatively small size of the customary extractor spring complicates the assembly and disassembly of the bolt especially under field conditions. Furthermore, difficulty has been experienced in providing adequate space for seating the extractor spring in the front end of the bolt without unduly weakening the strength thereof in such a critical area. In addition, conventional coil springs possess little or no damping properties and, therefore, especially in the case of relatively large caliber guns, are not capable of preventing repeated bouncing due to the forces encountered in riding over the rim of the cartridge case. Obviously, any continuation of this bouncing during the beginning of the recoil movement of the bolt could result in a failure to extract the fired cartridge case.

It is a general object of the present invention to provide a rugged and reliable means for resiliently mounting a pivotal cartridge case extractor in the front end of a longitudinally reciprocating bolt.

It is a particular object of this invention to provide an improved cartridge extractor which can be biased into engagement with the rim on a cartridge case without the necessity for utilizing a separate spring member.

In order to overcome the aforesaid difficulties encountered in the utilization of coiled or flat springs for biasing a pivotal extractor into gripping engagement with a rimmed cartridge case, this invention proposes that the extract-or be mounted on a torsion bar rather than the customary fixed pin of the prior art. It has been found that this can be satisfactorily accomplished if the extracfor is fixedly mounted on the bar which is, in turn, arranged to extend through the front end of the bolt and secured against rotation therein only at one end thereof. Thus, when the forward edge of the claw portion on the extractor strikes the base of the cartridge and is carnmed over the rim thereon by the continued forward movement of the bolt, the body of the torsion bar is correspondingly rotated to accumulate sufficient energy to bias the claw portion into the annular extractor groove adjacent the rL'n at the rear end of the cartridge case as the bolt moves into battery position. Such mounting arrangement can be utilized either with. a single extractor or a pair of identical extractors mounted on diametrically opposite sides of the bolt.

Other objects and advantages of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only and in which:

FIG. 1 is an elevational fragmentary view of a gun having a reciprocating bolt provided with an opposed pair of cartridge extractors, and being partially sectioned to show the manner in which one of the extractors is mounted for pivotal movement;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1 to show the opposed relationship of the dual extractors; and

FIG. 3 is an exploded view of an extractor assembly shown in perspective.

As illustrated in the drawings, the type of gun to which this invention is particularly adapted is provided with a stationary receiver 12 in which a bolt 14 is slidably mounted for longitudinal reciprocation into and out of battery position. A firing pin 16 is axially disposedin bolt 14 in position to be forwardly actuated by suitable means (not shown) into firing contact with the base of a cartridge 18 chambered in the breech end of a barrel Ztl.

A pair of vertical holes 22 are spaced apart in the forward end of bolt 14 to symmetrically straddle firing pin 16 as best shown in FIG. 2. Each hole 22 is rectangularly counterbored at one end, as indicated at 24, to receive the correspondingly shaped head 26 of a pin 28 extending upwardly through hole 22. Bolt 14 is also rectangularly slotted on opposite sides thereof, as shown at 3%), to intersect holes 22 and provide access for the substantially central mounting portion 32 on each of a pair of claw-type extractors 34. In the event only one extractor 34 is capable of providing the force necessary to withdraw a fired cartridge case from the firing chamber in barrel 2d, the other extractor may be conveniently utilized to assist in retaining the case in engagement with bolt 14 simply by eliminating the claw portion therefrom.

Extractor mounting portion 32 may be of any exterior configuration as long as it is of sutficient size to contain a rectangular hole 36 there/through adapted to receive a corresponding rectangular section 38 formed along one end of pin 28. The remainder of pin 28 is preferably cylindrical in contour and blends into rectangular section 33 without any appreciable change in diameter.

The forward end of each extractor 34 is contoured to form a claw 46 having a planar right-angled surface 42 of slightly smaller length than the height of the rim 44 adjacent the base of cartridge 18. A bevel 46 at the extreme forward end of claw 40 provides a cam surface for a purpose to be explained. The portion of extractor 34 which extends rearwardly beyond mounting portion 32 may be of any suitable configuration and length provided the contact thereof with the side of bolt 14 does not interfere with the extent of the pivotal movement required to override rim 44 on cartridge 18 as hereinafter described.

During the recoil movement imparted to bolt 14 by the firing of the chambered cartridge 18, extractors 34 grip rim 44, as best shown in FIG. 2, and, consequently, serve to withdraw the fired case from barrel 26. Ejection of the fired case and the feeding a new cartridge 18 into the counter-recoil path of bolt 14 are then accomplished in any conventional manner. As bolt 14 advanm, bevels 46 on extractors 34 move into contact with the base of the cartridge 18 to be chambered so that once the forward travel thereof is completed, the continued forward movement of bolt 14 causes extractors 34 to pivot outwardly over cartridge case rim 44. Since extractors 34 are fixedly mounted on pins 28 which are, in turn, free to rotate in bolt 14 except at the end provided with head 26, the body of each pin 28 is torsionally rotated by the outward pivotal movement of the extractor 34 thereon. Once gripping surface 42 on each extractor claw 4t rides over the periphery of rim t4, the torsional energy accumulated in pins 28 serves to bias such claw inwardly into the annular extractor groove forwardly adjacent rim 44.

It is, therefore, readily apparent that extractor mounting pins 28 act as torsion bars and supply the energy required to ensure complete engagement between extractors 34 and rim 44 on cartridge 18 at the conclusion of the forward movement of bolt 14 into battery position. Consequently, there is no need for any separate or additional spring to accomplish this necessary function of the extractor.

Furthermore, the aforesaid torsion bar arrangement provides far more effective damping of the pivotal movement imparted to the extractor than the type of extractor springs heretofore employed. This is a desirable improvement inasmuch as any tendency for the extractor to bounce upon return into gripping engagement with the rim on the cartridge is substantially reduced and, consequently, minimizes the possibi ity of the gun malfunction known as a failure to extract.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

We claim:

1. In a gun having a firing chamber and a longitudinally reciprocating bolt for ramming a rimmed cartridge into the chamber during the forward travel thereof, means for withdrawing the cartridge from the firing chamber during the rearward travel of the bolt comprising a rigid extactor pivotally mounted in the front end of the bolt in position to ride over the rim of the chambered cartridge and engage therewith at the conclusion of the foward travel of the bolt, a torsion pin extending transversely through the bolt having one end thereof in fixed engagement with said extractor, and means for retaining the opposite end of said pin against axial rotation in the bolt whereby the torsional energy imparted to said pin by the pivotal movement of said extractor required to ride over the cartridge rim biases said extractor into positive engagement therewith.

2. The combination defined in claim 1 wherein the fixed engagement of said extractor on said mounting pin is provided by a rectangular section along said pin engage- 4 able with a correspondingly shaped hole through said extractor.

3. In a gun having a firing chamber for rimmed carridges, a longitudinally reciprocating bolt for ramming a rimmed cartridge into the firing chamber during forward movement, and a rigid extractor pivotally disposed in the front end of the bolt to ride over the rim of the chambered cartridge and engage therewith for effecting the withdrawal thereof from the firing chamber during the rearward movement of the bolt, means for biasing the extractor into positive engagement with the rim of the cartridge comprising a torsion pin having a cylindical body extending through the bolt to terminate in an enlarged rectangular head, and means for fixedly securing the extractor to the end of said pin opposite said rectangular head, the bolt having a rectangular opening in one side for retaining said rectangular head against rotation so that the accumulation of torsional energy in said pin as the extractor rides over the cartridge rim is limited to said cylindrical body.

4. The combination defined in claim 3 wherein the extractor is formed with a claw portion having a bevel at the forward end thereof for contacting the base of the chambered cartridge during the forward movement or the bolt to pivot the extractor and impart torsional energy to said pin.

5. In a gun having a firing chamber, a longitudinally reciprocating bolt for ramming a rimmed cartridge into the chamber during the forward travel thereof, and a firing pin axially disposed in the bolt for firing the chambered cartridge, means for withdrawing the fired cartridge from the firing chamber during the rearward travel of the bolt comprising a pair of diametrically opposed rigid extractors pivotally mounted in the front end of the bolt to project therefrom in position to ride over the rim of the chambered cartridge for engagement therewith at the conclusion of the forward travel of the bolt, a pair of torsion pins extending through the bolt to straddle the firing pin, means for respectively and fixedly securing said extractors to the ends of said pins, and means in the bolt for retaining the opposite ends of each pin against the axial rotation imparted thereto by the pivotal movement of said extractors over the rim on the cartridge whereby the torsional energy thereby produced in said pins is utilized to bias said extractors into positive engagement with the cartridge rim.

References Cited by the Examiner UNITED STATES PATENTS 2,603,020 7/52 Hussey 4225 BENJAMIN A. BORCHELT, Primary Examiner.

FRED C. MATTERN, JR, Examiner. 

1. IN A GUN HAVING A FIRING CHAMBER AND A LONGITUDINALLY RECIPROCATING BOLT FOR RAMMING A RIMMED CARTRIDGE INTO THE CHAMBER DURING THE FORWARD TRAVEL THEREOF, MEANS FOR WITHDRAWING THE CARTRIDGE FROM THE FIRING CHAMBER DURING THE REARWARD TRAVEL OF THE BOLT COMPRISING A RIGID EXTRACTOR PIVOTALLY MOUNTED IN THE FRONT END OF THE BOLT IN POSITION TO RIDE OVER THE RIM OF THE CHAMBERED CARTRIDGE AND ENGAGE THEREWITH AT THE CONCLUSION OF THE FORWARD TRAVEL OF THE BOLT, A TORSION PIN EXTENDING TRANS- 